Images in clinical medicine. Leukocytosis and sublingual microvascular blood flow

Detection of Retinal Microvascular Changes with Optical Coherence Tomography Angiography in Patients with Acute Leukemia Without Retinopathy

INTRODUCTION

Acute leukemia often affects microcirculation perfusion. This study aimed to investigate retinal microvascular changes in patients with acute leukemia without retinopathy during clinical remission using optical coherence tomography angiography (OCTA) and to determine the correlation of these changes with systemic laboratory values.

METHODS

Thirty-eight patients in remission from acute leukemia with no retinopathy (NLR group) and 36 age-matched healthy individuals (control group) were included in this cross-sectional study. OCTA parameters, including the central foveal thickness (CFT), foveal avascular zone (FAZ) area, FAZ perimeter, acircularity index (AI), foveal density (FD300), and the vessel densities (VDs) of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris were analyzed in a 6 × 6 mm2 macular scan. Correlation and multiple linear regression analyses were conducted to identify potential systemic characteristics associated with these OCTA metrics.

RESULTS

AI (P = 0.034) and FD300 (P < 0.001) differed significantly between the NLR and control groups. The VD of SCP in the parafovea (P = 0.001) and of DCP in both the parafovea (P = 0.011) and perifovea (P = 0.001) were significantly lower in the NLR group than in the control group. In a multiple linear regression analysis, the reduced VD of the perifoveal DCP was significantly correlated with the increased international normalized ratio (standardized beta [STD β] = - 0.356; P = 0.047).

CONCLUSIONS

Macular microvascular changes can be observed during remission from acute leukemia antecedent to clinically visible retinal lesions. Hematological disturbances may be associated with microvascular impairments in preclinical leukemic retinopathy.

Retinal Microvascular Changes in Patients with Acute Leukemia

PURPOSE

To evaluate the retinal circulation in patients with active acute leukemia, to correlate the perfusion metrics with systemic laboratory values, and to assess the vascular perfusion after leukemia remission.

METHODS

Longitudinal study of 22 eyes from 12 patients with acute leukemia; healthy eyes were recruited as controls. All patients underwent optical coherence tomography (OCTA) at baseline. OCTA was repeated in case of morphological leukemia remission.

RESULTS

Patients' age ranged 37-74 years. All participants had a 20/20 vision. In all leukemic eyes, OCTA detected vascular alterations in the macula and the peripapillary region. Vessel density (VD) values in the superficial capillary plexus were lower in leukemia patients than controls (46.8±3.6 vs. 49.2±2%, p=0.08), irrespective of the presence of leukemic retinopathy (7 eyes, 32%). Lower VD was associated with lower white blood cells (p=0.09) and lower platelets (p=0.001). Reappearance of small capillaries, increase in VD, reduction in vessel diameter, and increase in fractal dimension was seen after remission.

CONCLUSION

Subclinical, reversible reduction in vessel density and complexity on OCTA occurs in patients with active acute leukemia and is presumably associated with bone marrow function failure. Further studies are warranted to explore its functional and prognostic significance.

Electronic health records: a critical appraisal of strengths and limitations

Electronic health record (EHR) was hailed as a major step towards making healthcare more transparent and accountable. All the developed nations digitised their health records which were meant to be safe, secure and could be accessed on demand. This was intended to benefit all stakeholders. However, the jury is still out if the EHR has been worth it. There have been incidences of data breaches despite cybersecurity checks and of manipulation compromising clinicians' integrity and patients' safety. EHRs have also been blamed for doctor burnout in overloading them with a largely avoidable administrative burden. The lack of interoperability amongst various EHR software systems is creating obstacles in seamless workflow. Artificial intelligence is now being used to overcome deficiencies of the EHR. Emerging data from real-world usage of EHR is providing useful inputs which would be helpful in making it a better system. This review critically appraises the current status and issues with the EHR and provides an overview of the key innovations which are being implemented to make the system more efficient for health care providers leading to a reduction in their administrative burden.

A comparison of the quality of image acquisition between two different sidestream dark field video-microscopes

Sidestream dark field (SDF) imaging enables direct visualisation of the microvasculature from which quantification of key variables is possible. The new MicroScan USB3 (MS-U) video-microscope is a hand-held SDF device that has undergone significant technical upgrades from its predecessor, the MicroScan Analogue (MS-A). The MS-U claims superior quality of sublingual microcirculatory image acquisition over the MS-A, however, this has yet to be robustly confirmed. In this manuscript, we therefore compare the quality of image acquisition between these two devices. The microcirculation of healthy volunteers was visualised to generate thirty video images for each device. Two independent raters, blinded to the device type, graded the quality of the images according to the six different traits in the Microcirculation Image Quality Score (MIQS) system. Chi-squared tests and Kappa statistics were used to compare not only the distribution of scores between the devices, but also agreement between raters. MS-U showed superior image quality over MS-A in three of out six MIQS traits; MS-U had significantly more optimal images by illumination (MS-U 95% optimal images, MS-A 70% optimal images (p-value 0.003)), by focus (MS-U 70% optimal images, MS-A 35% optimal images (p-value 0.002)) and by pressure (MS-U 72.5% optimal images, MS-A 47.5% optimal images (p-value 0.02)). For each trait, there was at least 85% agreement between the raters, and all the scores for each trait were independent of the rater (all p-values > 0.05). These results show that the new MS-U provides a superior quality of sublingual microcirculatory image acquisition when compared to old MS-A

Microvascular Dysfunction in the Critically Ill

Microvascular dysfunction is a frequent complication of many chronic and acute conditions, especially in the critically ill. Moreover, the severity of microvascular alterations is associated with development of organ dysfunction and poor outcome. The complexities and heterogeneity of critical illness, especially in the elderly patient, requires more mechanistically oriented clinical trials that monitor the effectiveness of existing therapies and of those to come. Recent advances in the ability to obtain physiologically based assessments of microcirculatory function at the bedside will make microcirculatory-guided resuscitation a point of care reality.

Why Rudolph's nose is red: observational study

OBJECTIVE

To characterise the functional morphology of the nasal microcirculation in humans in comparison with reindeer as a means of testing the hypothesis that the luminous red nose of Rudolph, one of the most well known reindeer pulling Santa Claus's sleigh, is due to the presence of a highly dense and rich nasal microcirculation.

DESIGN

Observational study.

SETTING

Tromsø, Norway (near the North Pole), and Amsterdam, the Netherlands.

PARTICIPANTS

Five healthy human volunteers, two adult reindeer, and a patient with grade 3 nasal polyposis.

MAIN OUTCOME MEASURES

Architecture of the microvasculature of the nasal septal mucosa and head of the inferior turbinates, kinetics of red blood cells, and real time reactivity of the microcirculation to topical medicines.

RESULTS

Similarities between human and reindeer nasal microcirculation were uncovered. Hairpin-like capillaries in the reindeers' nasal septal mucosa were rich in red blood cells, with a perfused vessel density of 20 (SD 0.7) mm/mm(2). Scattered crypt or gland-like structures surrounded by capillaries containing flowing red blood cells were found in human and reindeer noses. In a healthy volunteer, nasal microvascular reactivity was demonstrated by the application of a local anaesthetic with vasoconstrictor activity, which resulted in direct cessation of capillary blood flow. Abnormal microvasculature was observed in the patient with nasal polyposis.

CONCLUSIONS

The nasal microcirculation of reindeer is richly vascularised, with a vascular density 25% higher than that in humans. These results highlight the intrinsic physiological properties of Rudolph's legendary luminous red nose, which help to protect it from freezing during sleigh rides and to regulate the temperature of the reindeer's brain, factors essential for flying reindeer pulling Santa Claus's sleigh under extreme temperatures.

Septic shock and chemotherapy-induced cytopenia: effects on microcirculation

PURPOSE

Neutrophil and platelet activation and their interactions with endothelial cells are considered central features of sepsis-induced microcirculatory alterations. However, no study has evaluated the microvascular pattern of septic shock patients with chemotherapy-induced severe cytopenia.

METHODS

Demographic and hemodynamic variables together with sublingual microcirculation recording [orthogonal polarization spectral imaging enhanced by sidestream dark-field technology (OPS-SDF) videomicroscopy] were collected in four groups of subjects: septic shock (SS, N = 9), septic shock in cytopenic patients (NSS, N = 8), cytopenia without infection (NEUTR, N = 7), and healthy controls (CTRL, N = 13). Except for controls, all measurements were repeated after complete resolution of septic shock and/or neutropenia. Video files were processed using appropriate software tool and semiquantitatively evaluated [total vascular density (TVD, mm/mm(2)), perfused vessel density (PVD, mm/mm(2)), proportion of perfused vessels (PPV, %), mean flow index (MFI), and flow heterogeneity index (FHI)].

RESULTS

Compared with controls, there were statistically significant microcirculatory alterations within all tested groups of patients (TVD: SS = 8.8, NSS = 8.8, NEUTR = 9.1 versus CTRL = 12.6, p < 0.001; PVD: SS = 6.3, NSS = 6.1, NEUTR = 6.9 versus CTRL = 12.5, p < 0.001; PPV: SS = 71.6, NSS = 68.9, NEUTR = 73.3 versus CTRL = 98.7, p < 0.001; MFI: SS = 2.1, NSS = 1.9, NEUTR = 2.1 versus CTRL = 3.0, p < 0.05; FHI: SS = 1.0, NSS = 0.9, NEUTR = 0.6 versus CTRL = 0.0, p < 0.001). No significant differences were detected between SS, NSS, and NEUTR groups at baseline. Incomplete restoration of microcirculatory perfusion was observed after septic shock and/or neutropenia resolution with a trend towards better recovery in MFI and FHI variables in NSS as compared with SS patients.

CONCLUSIONS

Microvascular derangements in septic shock did not differ between noncytopenic and cytopenic patients. Our data might suggest that profound neutropenia and thrombocytopenia do not render microcirculation more resistant to sepsis-induced microvascular alterations. The role and mechanisms of microvascular alterations associated with chemotherapy-induced cytopenia warrant further investigation.

Improvement of sidestream dark field imaging with an image acquisition stabilizer

BACKGROUND

In the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS) for Sidestream Dark Field (SDF) imaging.

METHODS

The IAS is a stainless steel sterilizable ring which fits around the SDF probe tip. The IAS creates adhesion to the imaged tissue by application of negative pressure. The effects of the IAS on the sublingual microcirculatory flow velocities, the force required to induce pressure artifacts (PA), the time to acquire a stable image, and the duration of stable imaging were assessed in healthy volunteers. To demonstrate the clinical applicability of the SDF setup in combination with the IAS, simultaneous bilateral sublingual imaging of the microcirculation were performed during a lung recruitment maneuver (LRM) in mechanically ventilated critically ill patients. One SDF device was operated handheld; the second was fitted with the IAS and held in position by a mechanic arm. Lateral drift, number of losses of image stability and duration of stable imaging of the two methods were compared.

RESULTS

Five healthy volunteers were studied. The IAS did not affect microcirculatory flow velocities. A significantly greater force had to applied onto the tissue to induced PA with compared to without IAS (0.25 +/- 0.15 N without vs. 0.62 +/- 0.05 N with the IAS, p < 0.001). The IAS ensured an increased duration of a stable image sequence (8 +/- 2 s without vs. 42 +/- 8 s with the IAS, p < 0.001). The time required to obtain a stable image sequence was similar with and without the IAS. In eight mechanically ventilated patients undergoing a LRM the use of the IAS resulted in a significantly reduced image drifting and enabled the acquisition of significantly longer stable image sequences (24 +/- 5 s without vs. 67 +/- 14 s with the IAS, p = 0.006).

CONCLUSIONS

The present study has validated the use of an IAS for improvement of SDF imaging by demonstrating that the IAS did not affect microcirculatory perfusion in the microscopic field of view. The IAS improved both axial and lateral SDF image stability and thereby increased the critical force required to induce pressure artifacts. The IAS ensured a significantly increased duration of maintaining a stable image sequence.

Microcirculatory assessment in daily clinical practice - not yet ready but not too far!

ABSTRACT Shock is characterized by an alteration in tissue perfusion that may lead to tissue hypoxia. Recent guidelines recommend aggressive and early resuscitation therapy, but mortality rate is still unacceptably high. Unfortunately, traditional clinical surrogates used to guide resuscitation therapy poorly correlate with microcirculatory blood flow, a key determinant of tissue perfusion. New techniques that directly assess microcirculatory perfusion at the bedside have emerged as a complement to traditional macrohemodynamic parameters. These techniques have been supported by several studies showing microcirculatory alterations in different clinical settings. In addition, these microcirculatory alterations are related with outcome and persist regardless of arterial pressure normalization, being a better predictor of organ dysfunction and mortality than global hemodynamic and laboratory parameters. These findings allowed the concept of “microcirculatory-goal directed therapy”, which is now in its preliminary phase, as the impact of many interventions still needs to be assessed. Finally, microcirculation assessment has also been explored in other medical fields such as perioperative, systemic arterial hypertension, heart failure, and hyperviscosity syndromes. In this review, we shortly present the characteristics of microcirculation and the main determinants of capillary blood flow, and we discuss advantages and limitations of some recently available techniques to evaluate microcirculation at the bedside, and how they could be useful for the general clinician in daily practice.